A typical active matrix organic light-emitting diode (AMOLED) pixel circuit is shown in FIG. 1. In a data write phase, a transistor T1 is turned on under control of a first scan signal line S1, and a data voltage is written from a data line Dm to a gate of a driving transistor Td through the transistor T1. In a light emission phase, a single-pulse signal having a width comparable to that of a clock signal is supplied from a second scan signal line S2 to a gate of a switch transistor T2 such that the switch transistor T2 is driven to remain turned-on within a lapse of time corresponding to the pulse width. In this case, the OLED may be driven by a current flowing through the driving transistor Td and the switch transistor T2 to emit light.
Adjustment of grayscales of luminance may be achieved by adjusting the data voltage. However, there may be a large deviation between the adjusted grayscale and a desired grayscale, thereby affecting the display effect.
Therefore, there is a need for an alternative for adjusting the luminance of an image displayed by a display panel.